Have a resistive load (towel warmer) hooked to a triarc type remote switch (this one is from Crestron but they all pretty much work the same...). Load is too much so need to put a relay in the middle. Then the triarc switch will just handle a smaller load and be isolated from the resistive one.

Plan is add-on box next to current controller. Mount isolators to rear of box (unknown source or part), relay (seems like the easy part) and then a heat-sink in front...However I can't see how to finish the box on the wall or tie the heat-sink to the plate? I'm also a little mystified there isn't a box already that does....maybe I'm missing something.

Any ideas? It seems simple but the penalty for a mistake here seems to be starting a fire so I'm a little cautious...

I'm a bit mystified, too. I do not follow how a "relay in the middle" will allow the triac to handle a smaller load.

What is the wattage on the towel warmer? How much current can the triac pass? Is the triac in there to proportion power so the towel rack maintains an even temperature? Is the remote for on/off, or does it have to do with setting temp?

If not a schematic, then a wiring diagram with some ratings would be a big help.